1. Field of the Invention
The invention relates generally to telecommunications connectors and in particular to a telecommunications outlet having shielding members extending along contact tails.
2. Prior Art
Improvements in telecommunications systems have resulted in the ability to transmit voice and/or data signals along transmission lines at increasingly higher frequencies. Several industry standards that specify multiple performance levels of twisted-pair cabling components have been established. The primary references, considered by many to be the international benchmarks for commercially based telecommunications components and installations, are standards ANSI/TIA/EIA-568-A (/568) Commercial Building Telecommunications Cabling Standard and 150/IEC 11801 (/11801), generic cabling for customer premises. For example, Category 3, 4 and 5 cable and connecting hardware are specified in both /568 and /11801, as well as other national and regional specifications. In these specifications, transmission requirements for Category 3 components are specified up to 16 MHZ. Transmission requirements for Category 4 components are specified up to 20 MHZ. Transmission requirements for Category 5 components are specified up to 100 New standards are being developed continuously and currently it is expected that future standards will require transmission requirements of at least 600 MHZ. To achieve such transmission rates, fully shielded twisted pair cable will be necessary in which each pair is individually wrapped in a foil or screen. In addition, all pairs are wrapped together in a layer of foil or screen.
The above referenced transmission requirements also specify limits on near-end crosstalk (NEXT). Telecommunications connectors are organized in sets of pairs, typically made up of a tip and ring connector. As telecommunications connectors are reduced in size, adjacent pairs are placed closer to each other creating crosstalk between adjacent pairs. To comply with the near-end crosstalk requirements, a variety of techniques are used in the art.
U.S. Pat. No. 5,593,311 discloses a shielded compact data connector designed to reduce crosstalk between contacts of the connector. Pairs of contacts are placed within metallic channels. When the connectors are mated, the channels abut against each other to enclose each pair in a metallic shield. One disadvantage to the design in U.S. Pat. No. 5,593,311 is that no shield is provided for contact tails extending beyond the bottom of a connector housing. As a result, the shielding effect is reduced and crosstalk occurs between the contact tails. Thus, there is a perceived need in the art for a connector having improved pair shielding.
The above-discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by the enhanced performance telecommunication outlet of the present invention. In one embodiment, a telecommunication outlet for mounting on a printed circuit board, comprises: a conductive housing having a top, a bottom, side walls joining the top and bottom, and a rear having an outer shield, an inner shield and a center shield joining the outer shield and the inner shield, the top, bottom, side walls and rear being in electrical contact; a vertical shield extending between the top and bottom; and a horizontal shield positioned between the top and bottom and between the sidewalls, the horizontal shield and the vertical shield defining four quadrants, each of the four quadrants containing contacts corresponding to a tip and ring pair; wherein the contacts each have a contact tail extending downwards beyond the printed circuit board, and the inner shield has an extension extending downwards beyond the printed circuit board, the extension being disposed between a first set and a second set of the contact tails. The printed circuit board includes metal plated holes for receiving the respective contact tails and a metal plated slot for receiving the extension of said inner shield. Preferably, the length of the protruding portion of the inner shield extension is substantially equal to the length of the protruding portion of the contact tails.
In a further embodiment of the present invention, the vertical shield of the telecommunication outlet further includes an extension extending downwards beyond the printed circuit board. When the contact tails are arranged in rows and columns, the inner shield extension is disposed between two rows of the contact tails and the vertical shield extension is disposed between two columns of the contact tails. In this embodiment, the printed circuit board further includes a metal plated slot for receiving the vertical shield extension. The vertical shield extension and the inner shield extension form a cross structure extending downwards beyond the printed circuit board, in which the cross structure defines four quadrants each for shielding the contact tails of a tip and ring pair.